CeO₂-ZrO₂ nanoparticle-modified enzymatic lactate biosensors with reduced oxygen susceptibility

In the present work, the development of novel CeO₂-ZrO₂ nanoparticle-modified sensing platforms was described to address the oxygen dependency of lactate oxidase enzyme-based electrochemical lactate biosensors. Using engineered electrode modification, it was aimed to construct enzymatic lactate sensors capable of working in O₂-depleted environments. In this regard, CeO₂-ZrO₂ nanoparticles were chosen as electrode modifiers due to their high oxygen release and uptake properties. The nanoparticles were prepared using a facile chemical synthesis method and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and N₂ adsorption methods. The XRD and TEM results confirmed the successful synthesis of CeO₂-ZrO₂ nanoparticles and a physical surface area of 76.1 m² g^-1 was measured by BET method. The electrochemical performance results demonstrated that CeO₂-ZrO₂ nanoparticle-modified biosensors showed high sensitivities regardless of the subjected environments. In contrast to conventional enzymatic lactate biosensors, novel sensor design experienced only a slight drop in the response in O₂-depleted solutions, confirming that the O₂-susceptibility of the lactate biosensors was diminished significantly. The novel biosensor design showed a high sensitivity of 138.9 ± 1.2 μA. mM^-1. cm^-2 with the linear range of 2.5 μM-0.6 mM.